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Image Deblurring in Demanding Conditions
Kotera, Jan ; Šroubek, Filip (advisor) ; Portilla, Javier (referee) ; Jiřík, Radovan (referee)
Title: Image Deblurring in Demanding Conditions Author: Jan Kotera Department: Institute of Information Theory and Automation, Czech Academy of Sciences Supervisor: Doc. Ing. Filip Šroubek, Ph.D., DSc., Institute of Information Theory and Automation, Czech Academy of Sciences Abstract: Image deblurring is a computer vision task consisting of removing blur from image, the objective is to recover the sharp image corresponding to the blurred input. If the nature and shape of the blur is unknown and must be estimated from the input image, image deblurring is called blind and naturally presents a more difficult problem. This thesis focuses on two primary topics related to blind image deblurring. In the first part we work with the standard image deblurring based on the common convolution blur model and present a method of increasing robustness of the deblur- ring to phenomena violating the linear acquisition model, such as for example inten- sity clipping caused by sensor saturation in overexposed pixels. If not properly taken care of, these effects significantly decrease accuracy of the blur estimation and visual quality of the restored image. Rather than tailoring the deblurring method explicitly for each particular type of acquisition model violation we present a general approach based on flexible automatic...
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Demosaicing as an ill-posed inverse problem
Mariničová, Veronika ; Šroubek, Filip (advisor) ; Hnětynková, Iveta (referee)
Color information of a scene is only recorded partially by a digital camera.Specifically, only one of the red, green, and blue color components is sampled at each pixel.The missing color values must be estimated － a process called demosaicing. Demosaicing can be solved as an individual step in the image processing pipeline. In this case, any errors and artefacts produced by this step are carried over into further steps in the image processing pipeline and are possibly magnified. Alternatively, we can try to resolve several degradations at once in a joint solution, which eliminates this effect. We present one such solution, that in addition to demosaicing, also jointly solves denoising, deconvolution, and super-resolution in the form of a convex optimization problem. We provide an overview of demosaicing methods and evaluate the results from our solution against selected existing methods.
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Methodology for breast ultrasound examination
Vydra, J. ; Daneš, J. ; Bartoš, Michal ; Šroubek, Filip ; Petr, L. ; Zitová, Barbara
The aim of the proposed project is the development of a new ultrasonic equipment (US), allowing early detection of breast cancer and reduce the need to use the ionizing radiation during examinations. The aim is to eliminate the disadvantages of current ultrasonic systems in the diagnosis of breast cancer, which hinders its use. The target parameters include prospecting and automated description using parameters (size, texture), description of the situation, which is able to testify about the disease, combining individual images (registration) leading to the creation of 3D display - thus ensuring reproducibility UZ shaping and security testing the entire organ. At the same time the newly developed ultrasonic probe allows better capture the characteristics of bearings including microcalcifications. Software solution enables to follow the coverage of the breast examination. The areas which were omitted are detected and highlighted.
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Removal of JPEG compression artefacts in image data
Lopata, Jan ; Kučera, Václav (advisor) ; Šroubek, Filip (referee)
This thesis is concerned with the removal of artefacts typical for JPEG im- age compression. First, we describe the mathematical formulation of the JPEG format and the problem of artefact removal. We then formulate the problem as an optimization problem, where the minimized functional is obtained via Bayes' theorem and complex wavelets. We describe proximal operators and algorithms and apply them to the minimization of the given functional. The final algorithm is implemented in MATLAB and tested on several test problems. 1
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Výpočetní fotografie ve světelném poli a aplikace na panoramatické snímky
Kučera, Jan ; Šroubek, Filip (advisor) ; Šik, Martin (referee)
The digital photography is still trying to catch-up with its analogous counterpart and recording light direction is one of the most recent area of interest. The first and still the only one light-field camera for consumers, the Lytro camera, has reached market in 2011. This work introduces the light-field theory and recording with special emphasis on illustrating the principles in 2D, gives an overview of current hardware and ongoing research in the area and analyses the Lytro camera itself, describing the closed file formats and protocols it uses so that further research can be conducted. An important contribution of the work is a .NET portable library for developers, supplemented by a file editor as well as an application for wireless communication with the camera based on the library. Finally, the theory is used to discuss implications for light-field registration and linear panoramas. Powered by TCPDF (www.tcpdf.org)
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Použití gyroskopů a akcelerometrů k doostření fotografií pořízených mobilním telefonem
Šindelář, Ondřej ; Šroubek, Filip (advisor) ; Wilkie, Alexander (referee)
Long exposure handheld photography is coupled with the problem of blurring, which is difficult to remove without additional information. The goal of this work was to utilize motion sensors contained in modern smartphones to detect exact motion track of the image sensor during the exposure and then to remove the blur from the resulting photograph according to this data. A system was proposed which performs deconvolution using a kernel from the recorded gyroscope data. An implementation on Android platform was proved on a test smartphone device.
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Odstranění rozmazání pomocí dvou snímků s různou délkou expozice
Sabo, Jozef ; Šroubek, Filip (advisor) ; Horáček, Jan (referee)
In the presented work we study methods of image deblurring using two images of the same scene with different exposure times, focusing on two main approach categories, the so called deconvolution and non-deconvolution methods. We present theoretical backgrounds on both categories and evaluate their limitations and advantages. We dedicate one section to a comparison of both method categories on test data (images) for which we use a MATLAB implementation of the methods. We also compare the effectiveness of said methods against the results of a selected single- image de-noising algorithm. We do not focus at computational efficiency of algorithms and work with grayscale images only.
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Odstranění rozmazání pomocí dvou snímků s různou délkou expozice
Sabo, Jozef ; Šroubek, Filip (advisor) ; Horáček, Jan (referee)
In the presented work we study the methods of image deblurring using two images of the same scene with different exposure times, focusing on two main approach categories, so called deconvolution and non-deconvolution methods. We present theoretical backgrounds on both categories and evaluate their limitations and advantages. We dedicate one section to compare both method categories on test data (images) for which we our MATLAB implementation of the methods. We also compare the effectiveness of said methods against the results of a selected single-image de-noising algorithm. We do not focus at computational efficiency of algorithms and work with single-channel images only.
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Reconstruction of motion blurred digital photographs
Papež, Michal ; Šroubek, Filip (referee) ; Pelikán, Josef (advisor)
In the present work we study digital reconstruction techniques of photographs that were damaged by simple camera motion during exposition. The work describes and compares procedures of image reconstruction in spatial and frequency domain. Special attention was given to algorithms of inverse filtration type. One of them was modi ed for restoration purpose. Another algorithms for estimating camera movement during exposition and inverse lter adjustment were designed and proposed. The in fluence of noise on the quality of reconstruction was studied. Another task was to design and implement an automatic tool for reconstruction. The proposed algorithms were then tested and evaluated on the base of this tool. Although the quality of reconstructed images is not on the expected level for common undamaged photographs, they should satisfy the requirements for usual technical purposes. Comparing the damaged and reconstructed images the improvement is evident.
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